[au8er]

Often times chirality is not just a fun quirk. For certain drugs, the left handed and the right handed versions can have completely different effects on the human body: https://en.wikipedia.org/wiki/Chiral_drugs#Drug_toxicity. To avoid making the wrong type of drug, a specific way of producing the chemical molecule has to be derived: https://en.wikipedia.org/wiki/Enantioselective_synthesis.

[howard941]

And sometimes it doesn't change much at all except for the patent and withdrawal as with citalopram/escitalopram (generic Celexa/Lexapro).